Berlin 2012 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 17: Poster Session

MM 17.19: Poster

Montag, 26. März 2012, 17:00–19:00, Poster B

Phason flips in quasicrystals: Interpretation of HRTEM data using kinetic Monte Carlo simulations — •Hansjörg Lipp and Hans-Rainer Trebin — Institut für Theoretische und Angewandte Physik, Universität Stuttgart, Germany

HRTEM observations of decagonal Quasicrystals by Edagawa et al. [1] show that phason flips can be observed directly as spots which vanish or appear erratically. The spots can be interpreted as clusters of atoms, which move coherently. Compared to the time scale of atomic jumps, this process is very slow, flips occur in periods of seconds or even minutes.

On the one hand, we analyze the temporal evolution and statistical properties of the spots shown on HRTEM images provided by K. Edagawa. On the other hand, we perform kinetic Monte Carlo simulations [2], using several statistical model systems, e.g. based on a structure model for d-Al-Cu-Co suggested by Zeger et al. [3]. There rings of ten atoms can perform flips by collective motion of atoms inside decagonal double layers.

We relate the experimental data to our simulation results, and demonstrate how flip frequencies depend on the number of decagonal layers and on the strength of their interaction.

[1] K. Edagawa et al., Phys. Rev. Lett. 85, 1674 (2000)

[2] A. B. Bortz et al., J. Comput. Phys. 17, 10 (1975)

[3] G. Zeger and H.-R. Trebin, Phys. Rev. B 54, R720 (1996)